Important Notice

The pages on this site contain documentation for very old MS-DOS software, purely for historical purposes. If you're looking for up-to-date documentation, particularly for programming, you should not rely on the information found here, as it will be woefully out of date.

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  Description:  Get MS-DOS Version Number
 
  Returns the version number of the host MS-DOS operating system. This
  function is used by application programs to determine the capabilities
  of their environment.
 
  Input             Output
  ══════            ═══════════════════════════════════════════════════
  AH=30H            If running under MS-DOS version 1
  AL=00H            If running under MS-DOS version 2.0 and later
                    AL=major version number (MS-DOS 3.1 = 3, etc.)
                    AH=minor version number (MS-DOS 3.1 = 0AH, etc.)
                    BH=Original Equipment Manufacturer's (OEM's) serial
                       number (OEM dependent--usually 00H for IBM's
                       PC-DOS, 0FFH or other values for MS-DOS)
                    BL:CX=24-bit user serial number (optional, OEM
                          dependent)
                                    -♦-